The field of the invention relates to automatic injection devices, i.e. autoinjectors, and particularly autoinjectors, including one or more end-of-dose visual indicators.
Automatic injection syringes, also referred to as “autoinjectors” include features that provide for an easy-to-use and automatic administration of an injectable drug solution or medicine. Autoinjectors are typically designed to have a push-pen design. The push-pen design allows an individual to initiate a self-injection literally at the push of a button or upon activation of a similar trigger that initiates self-injection. As such, autoinjectors are fairly simple to use, particularly in times when an individual may be experiencing stress, pain, and/or other medical ailments that would make self-injection with traditional syringes difficult.
Some types of autoinjectors are provided with the drug solution or medicine pre-loaded into a drug container, such as a syringe, or cartridge. When the drug solution or medicine is pre-loaded, the autoinjector is typically sold, having a predetermined, standardized unit dose. Without a distinct visual, audible and/or tactile indication to signal the complete dose has been administered, a user may become confused or impatient and remove the autoinjector from the injection site prematurely, losing some portion of the medicine. To address this issue, some autoinjectors described in the prior art, in particular non-retracting autoinjectors, come with instructions to the user to hold the injector against the injection site of the user much longer than the time actually required to complete the injection. To comply with these instructions, the user must therefore routinely experience the discomfort and distress of the hypodermic needle residing within the injection site longer than truly necessary.
For these reasons, among others, there is a need for improved autoinjectors that allow a user to clearly determine when the dose of medicine has been fully delivered. The embodiments of the invention fulfill this need and provide further related advantages, as described herein.